显式与隐式调用ToString（）

Question

Is there any benefit in calling the ToString() method on a string builder when the method call accepts the type object as it's parameter?

StringBuilder sb = new StringBuilder("Hello");

System.Console.WriteLine(sb);

OR

System.Console.WriteLine(sb.ToString());

From what I know the WriteLine takes an object as an overload, my guess is the ToString() method is then called on the object, which then calls the StringBuilder.ToString() method and returns the expected string value.

So again, is there any benefit in explictly calling ToString()? Could you please justify your answer?

Answer 1

The only benefit is that it is clear what you're doing. If you can state something explicitly do it - it makes the code more readable.

Answer 2

"my guess is the ToString() method is then called on the object"

If you look at MSDN you see that there is no overload that consumes a StringBuilder directly, so the one which accepts anything( object ) is used.

So your guess was correct, it will just call ToString .

If value is null, only the line terminator is written. Otherwise, the ToString method of value is called to produce its string representation, and the resulting string is written to the standard output stream.

Then i would prefer to call it myself since it's more readable and you gain nothing by passing the StringBuilder .

Answer 3

Is there any benefit in explicitly calling ToString()?

Console.WriteLine(object) will first check if the object is null and if so simply output an empty line. Calling ToString on a null object will result in a NullReferenceException.

So WriteLine(object) has built in null-safety, and the result for null will be the same as a non-null object that outputs an empty string. Depending on the context, that null safety could be convenient, or it could cause undesired behavior.

In short, it's more beneficial to call ToString() if you don't want a NullReferenceException to be suppressed.

Answer 4

No, there's no benefit. Tools with good static analysis capabilities like ReSharper will actually let you know that the call is redundant and can be safely removed.